book on (third-person singular simple present books on, present participle booking on, simple past and past participle booked on)
- To register (for duty).
2023 August 23, “Network News: RAIB cites driver fatigue as factor in 28mph collision”, in RAIL, number 990, page 12:Having woken at 0900 the previous morning, he had not slept during the day and had already been awake for 11 hours when he booked on.